Hydraulic throttle control



March 26, 1968 K. R. MoFr-'ETT 3,374,745

HYDRAULIC THROTTLE CONTROL Filed Oct. 7, 1966 034100,44 5555/025, MEM/0,01 im KVM/f5 United States Patent Oice 3,374,745 HYDRAULIC THROTILE CONTROL Kenneth R. Moffett, Euclid, Ohio, assignor to Hunter Manufacturing Company, Solon, Ohio, a corporation of Ohio Filed Oct. 7, 1966, Ser. No. 585,065

6 Claims. (Cl. 1031-.-16)

This invention relates to an automatic speed control device for internal combustion engines and more particularly to an automatic throttle control device for the engines of motor trucks embodying hydraulically-operated devices such as dump bodies, lift platforms and the like in which the hydraulic pressure for operation of the device is furnished by a pump driven by a power take-olf from the truck engine.

Large numbers of trucks having hydraulic devices operated by power take-off means driven by the engine are in use at the present time. Such trucks customarily embody a hydraulic motor, usually in the form f a cylinder arranged to actuate a dump body, lift platform andthe like or to perform some other desired function; a valve for controlling the ow of fluid to the hydraulic cylinder, the valve ordinarily being disposed outside of the cab of the truck at a point where the operator can observe the motion of the body, platform or the like; a pump which pumps hydraulic liuid under pressure to the cylinder; appropriate fluid connections for the devices; and a power take-off usually embodying auxiliary gearing so that the main truck engine can be employed to drive the pump.

The ordinary idling speed of the engine is not sufficient to furnish fluid under adequate pressure to operate the hydraulic cylinder at a reasonably rapid rate of speed. Accordingly, automatic throttle controls have been employed to increase the speed of the internal combustion engine in response to increases in the hydraulic pressure at the output of the pump driven through the usual power take-off unit by the truck transmission. Examples of these automatic throttle controls are disclosed in Fotte Patent 2,690,712, issued Oct. 5, 1954, and Stratton Patent 2,931,305, issued April 5, 1960. v

According to the present invention, an improved hydraulic throttle control device and method for adjusting saine are provided for cooperation with the carburetor throttle of the truck engine which actuator is adjustable for widely -varying hydraulic pressures and accelerator rod strokes. This actuator may be quickly and `easily inf stalled and adjusted to permit the engine to operate at idling speed whenever the back pressure of the pump is at a comparatively low value, and open the throttle a predetermined amount to give the desired engine speed whenever Athe hydraulic cylinder is operated 'to lift the body, platform or the like; i.e., Whenever the back pressure on the outlet side of the pump Vexceeds a predetermined amount.

nA general object of the present invention is the provision of a simple, substantially foolproof device for controlling the speed of operation of truck engines so as to automatically, increase the speed of the engine whenever it is desired to lift a load by the hydraulic cylinder and automatically to reduce the engine speed to the idling rate when the load is removed.

Another object is the provision of a sturdy device of this character which can be readily installed on and adjusted to cooperate with an existing truck and in connection with substantially all conventional hydraulic systems.

A further object is the provision of such a device which can be adjusted to suit the widely varying requirements of various installations and a wide range of operating conditions.

Further objects and advantages of the invention will become apparent from the following description of a pre- 3,374,745 Patented Mar. 26, 1968 ferred form thereof, reference being made to the accompanying drawings. The essential characteristics are summarized in the claims.

FIGURE 1 is a perspective view of one embodiment of throttle control device according to this invention; and,

FIGURE 2 is a combined sectional View in elevation of the control device of FIGURE 1, a fragmentary view of an engine and carburetor, and a combined block and pictorial diagram of a control system interconnecting the elements.

Referring now to the drawings, FIGURE 1 shows an example of a throttle control 10 according to one embodiment of this invention. Throttle control 10 includes a housing assembly 11 which is made of a suitable metallic material such as steel or iron. The housing assembly is preferably generally L-shaped in elevation as best seen in FIGURE 2, and is provided with an L-shaped slot 13 in which is pivotally mounted a suitable leaf-type spring 12. The leaf spring 12 is pivotally held against a pivot pin or fulcrum 14 by means of a low pressure adjusting screw 15 and a piston 16 on opposite sides of pin 14. Preferably, pin 14 includes a threaded portion, not shown, which threadably engages housing 11 and may advantageously be quickly and easily moved to different locations designated by letters A, B, C and D in FIGURE 1 to change the movement produced by the force exerted by piston 16 on spring 12. The setting of low pressure adjusting lscrew 15 determines the initial or lowest hydraulic pressure required to actuate throttle control 10 in a manner which will be subsequently described in detail.

The housing assembly 11 also includes a high engine speed adjusting screw 17 positioned on the opposite side of the pivot screw 14 from the lo w pressure adjusting screw 15 and positioned in the path of the spring 12. Screw 17 limits the spring deflection to the left, as viewed in FIGURE 2, as indicated by the dotted outline 12a.

Spring 12 is deflected by piston 16 which is slidably mounted in a cylinder 18 and moved by pressurized fluid in the hydraulic motor system in a manner which will be subsequently described. The piston 16 includes a circular recess 19 intermediate its ends which recess receives a suitable O-ring 20 to provide good fluid sealing relationship with the bore of cylinder 18. Low pressure adjusting screw 15 has a rounded tip 21 which engages the edge of a circular hole 22 in spring 12.

The means for supplying fluid under pressure to the cylinder 18 includes a nipple 24 threadably engaging the end of cylinder 18 remote from the spring 12 which nip'- ple threadably receives a suitably threaded coupling member 25 on the end of a fluid conduit 26. Fluid conduit 26 receives pressurized fluid from a pump 27 in a manner well-known in the art. Pump 27 is mechanically coupled to a power take-olf 28 which in turn is mechanically driven by the internal combustion engine 30.

The internal combustion engine 30 includes a carburetor 32 having a conventional carburetor linkage 33 and accelerator rod 34. The housing assembly 11 is preferably mounted on the engine 30 in an'y convenient manner such as by a mounting bracket and screws, not shown, which screws threadably engage mounting. holes 35. Also, housing 11 is aligned in a plane containing the axis of the accelerator rod 34 to facilitate the mechanical coupling between the accelerator rod 34 and leaf spring The mechanical coupling means for coupling leaf spring 12 to the accelerator rod 34 includes a threaded actuating rod 40 having a nut 42 on each side of the spring 12. Threaded rod 40 and nuts 42 constitute a line adjustment means for tensioning a chain assembly 43 which is employed to connect the actuating rod 40 to the accelerator rod 34. The chain assembly 43 terminates in a clip and screw assembly 44 which clamps against the periphery of the accelerator rod 34 and includes the'adjusting screw 45 so that the clip may be loosened, moved longitudinally relative to the accelerator rod and tightened in any convenient position. The chain assembly includes a swivel type clip 47 which clips over a ball-type end 48 of the actuating rod 40.

Y 'The hydraulic system may be of the type shown in Foote Patent 2,690,712 in which the pump supplies fluid under pressure to a control valve 50 having a valve control handle 51. Movement of handle 51 controlsthe supply ofpressurized iluid through a conduit 52 to a cylinder 53 containing a conventional piston 54. Only fragments of the cylinder and piston S3, 54 are shown,

the remaining portions being conventional structures for performing suitable Work operations. Subject to the nonoperation of the valve 50, uid is returned from the pump 27 through a conduit 58, a reservoir 59 and a pipe 60 to the pump 27. The manner of adjusting the throttle control will now be described in detail.

Because the throttle control is adapted to be used with hydraulic systems employing a wide range of pressures and With engines having a wide range of accelerator rod strokes, the first step in adjusting the throttle control is to select the required spring rate. The term spring rate as used herein means the force required to produce a given deliection of the spring 12 at the point where the rod 40 is connected to it and is a numerical value depending upon the desired movement of the throttle rod and the difference |between the hydraulic pressure in the cylinder 18 when the engine 30 is idling and the pressure in the cylinder 18 when the engine is at normal operating speed and is adjusted by the combination of positioning the pivot pin 14 in one of holes A, B', C or D and positioning the actuating rod 40 in one of holes a, b, c or d in spring 12.

It will be evident that the stillness and rate of the spring are reduced by moving the pivot pin downwardly, in the device shown in the drawing, from A to C, for example. Also, the amount of movement of the throttle rod for a given deflection of the spring is reducedV by moving the point of connection of the rod 40 to the spring downwardly from b to c, for example, thus increasing theY spring rate. These changes are reflected in Table I Vbelow which gives spring rates as defined above for a Y typical device embodying the invention.

To determine the required spring rate, the engine 30 is set to its desired idling speed with the operating valve 50 in its open center position. A reading is now taken on designated with the corresponding letters. Thus if the spring rate were determined to be 720, the setting Db would be employed, i.e., pivot pin 14 would be located in its lowermost hole as shown in FIGURES 1 and 2 and actuating'rod 40 would be located in the second leaf spring hole from the top as best seen in FIGURE l. If, however, the spring rate were 1200, the setting would be Ca meaning that the pivot pin 14 would be moved up to the next higher hole C and the actuator rod 40 would be moved to its highest hole a, on leaf spring 12.

An example of the spring rate calculation based on pressure differential is as Yfollowsi assume that the rst pressure with the engine 30 idling is 100 p.s.i. and presa hydraulic pressure gauge 48 located in the pressure supply line 49 between the pump 27 and the valve 50. This pressure is recorded. The throttle accelerator rod 34 `is'nowmanually advanced to bring the engine 30 up to its operating speed with the vlave 50 still in its open center position. The system back pressure noted on gauge 48v is now recorded and the distance that the accelerator has been moved to bring the engine up to opearting speed is also measured and recorded. The required throttle Vcontrol springl rate is the difference between theV two pressure readings divided by the accelerator rod strokes. From the spring rate Table I the spring rate is selected which is equal to or next higher than the resultant answer obtained by the mathematical operation described above.

TABLE Lr-SPRING RATE WHEN PRESSURES AND STROKE ARE KNOWN Spring Rate 2, 450 3,000 3, 670 4,670 5,200 6, 350 8,050 10,100

The setting, which constitutes a 4combination of a capital letter and a small letter in Table I, refers to theV positions of the pivot pin 14 and the actuating rod 40, re-

spectively, relative to their respective holes which are sure at operating speed is 400 p.s.i. Thus the difference in pressure is 300 p.s.i. Also, assumerthat the stroke of the accelerator Yrod is of an inch. The pressure differential provided by the accelerator rod stroke is 300. This divided by 0.0625 of an inch gives a spring rate'of 4800, which is an arbitrary number based on the force exerted by the piston divided by the required movement.

of the accelerator rod. From Table I, the nexthighef spring rate is 5200 and the spring rate setting for the throttle control is Aa. Thus the pivot pin 14 Vis located in the uppermost holeA closest to the piston andthe actuating rod 40 is located at the top hole a in the leaf spring 12 as viewed in FIGURE 1.

For the purpose of this particular table, the leaf spring is 3A by .09 ilat annealed spring steel, S.A.E. 1095, which has been heat treated, 'oil quenched and tempered to 50-54, Rockwell C. The overall length is 61A inches,Y the distance between hole 22 which is engaged bythe end 21 of low pressure adjustment screw 15 and hole d yfor receiving actuating rod 40 is 4%, inches and the remaining holes for the actuating rod are spaced 1/2 inch apart. The hole D which receives pin 14 is 3A: of an inch from and transverse to the axis of ther/adjusting screw 15. The hole C is 1%6 of an inch from the center of the hole D, the hole D is of an inch from the hole C and the hole A is 1/2 of an inch from the hole D. The diam'-V eter of cylinder 18 is 1% of an inch.

' lf vthe system pressures are not available, an approximate method can `be employed which is based on the assumption that* the dilerence in pump outlet pressure between idling and operating engine speeds equals 200 lbs. per square inch. The accelerator rod is manually moved axially to increase the engine speed from idlingY Setting 'Da Db DC `:Dd CIL Cb CC Cd Stroke 964 1364 15/64 'Kn 11,64 z M; %4

' Setting Bt! Bb B6 Bd All Ab AC Ad Stroke.A z 64 lis 64 64 les l: 64

AfterV the spring rate has been selected, and pivot pin 14 and threaded rod 40 have been assembled in ltheir designated holes, the throttle control is adjusted in the following manner:Y The high speed adjusting screw 17 is adjusted until its ends bear against leaf spring 12. The purpose of this adjustment is to prevent accidental Yracing of the engine and high pressures which would be developed by the pump 27. With valve'51 centered and the pump under no load, the engine is operated to drive the Apun-ip and the carburetor idle control is adjusted to'bring the engine up to the required idle speed in a manner'wellknown in the art. The chain adjusting screw or 'actuating rod 40 is adjusted to take up any slack in the chain 43V and nuts 42 are tightened. 'Ihe chain should not be slackY Y TABLE II.-SPRING RATE VWHENYSTROK ONLY ISA Y KNOWN j .l

but should not be so tight as to prevent the engine from returning t0 idle Speed after operation of. accelerator pedal. The next step involves adjusting low pressureadjustment screw 15. The high speed adjustment screw 17 is backed out one turn. The engine 30 is idled and. the pump 27 driven through power take-oit 28, preferably, the oil in the hydraulic system cool. Screw 15 is backed out until the engine speed increases. Screw 15 is turned vvin until the carburetor throttle closes and the engine returns to idle speed. rIhe high speed actuating screwV 1 7 is now adjusted for the proper limiting of' the operating: speed of the engine with valve 50 operated to load the pump 27.

Assume that the pressures are not known `and that the accelerator rod movement is. 1A inch. From Table II the next lower stroke is 1%.; of an inch and the setting for the throttle control is Dc. Thus the pivot pin 14 islocated in the lowermost hole corresponding to its position shown in FIGURE 2 and the actuating rod 40 is located in the third hole from the outermost end of the spring. With these settings, the control chain, the low pressure sc rew 15 and the high speed adjusting screw 17 are adjusted in a anner reviously described. mit a stlitisfactory adjustment cannot be obtained, diie. to the throttle opening upon increasing pressure but failing to return to idle position upon reducing pressure, then the low pressure adjusting screw 15 is backed out to remove the tension on leaf spring 12, pivot screw 14 is moved one hole closer to piston 16 and the steps of setting the low pressure screw and the high pressure screw ated. areifrllig throttle opens and closes but fails to bring the engine up to the desired speed, the high speed adjustment screw 17 is backed out Mt of a turn or the actuating rod 40 is moved one hole closer to the outer or upper end of the leaf spring and the high speed adjusting screw 17 is readjusted. If the engine speed does not remain at idle when the pump is engaged, the low pressure adjusting screw is rotated clockwise to return the engine to idle. The high speed adjusting screw 17 is then reset. If the engine 30 slows down or stalls before the throttle control operates to open the throttle, the low pressure screw is backed off until the throttle control operates and the engine r.p.m. increases. Any slack existing in the chain 43 is eliminated by loosening nuts 4 2, tightening the actuating rod 40 and locking it in a position relative e s rin 12 b means of nuts 42.

toltlioni thi fordgoing discussion of the control device and the method of installing and adjusting same, it is apparent that the invention constitutes a highlyl exible control device capable of adaption to and adjustment with a large variety of hydraulic systems and internal combustion engines. While one illustrative embodiment of the device and two illustrative examples of the method of adjusting same have been described, it will be understood that other embodiments of the device and method can vbe employed without departing from the spirit and scope of this invention.

What is claimed is: D

1. An automatic control device for controlling the throttle of an engine driving a hydraulic pump, said automatic control device comprising a housing, a cylinder in said housing, a piston in said cylinder, a conduit connected to one end of said cylinder and communicating with the outlet side of said pump, whereby pressure on the outlet of said pump tends to move said piston away from said one end of said cylinder toward the other end of said cylinder, leaf-spring means in said housing and having a first end engaging said =piston for moving said piston toward said one end of said cylinder and a second end, a pivot pin engaging said leaf-spring means intermediate the ends of said leaf-spring means, a first adjustable screw means positioned to engage said spring means on one side thereof for limiting travel of said spring means in response to pressure in said cylinder, a second adjustable screw means engaging the opposite side of 6 said spring means from said rst screw means and at a point on the opposite side of said pivotpin'from said rst screw means for adjusting the force exerted by said spring means on said piston, and coupling means operatively coupling said leaf-spring means to the throttle to open the throttle in response to an increase in iiuid pressure in said cylinder and to permit the throttle to close when the iiuid pressure in said'cylinder is reduced.

2. An automatic control device for controlling the throttle of an engine operating a pump, said automatic control device comprising a housing having an elongated slot therein, a cylinder in said housing having one open end, a piston in said cylinder, a liuid conduit connecting said cylinder with the outlet side of said pump, whereby pressure on the .outlet side of s'aid pump tends to move said piston in one direction, fulcrum means positioned in said slot with the fulcrum means axis in a plane transverse the piston axis, leaf-spring means positioned in said slot against said fulcrum means and engaging said piston adjacent said open end of said cylinder for moving said piston in a direction away from said open end, a lirst adjustable means associated with said spring means for limiting the bending movement of said spring means and the travel of said piston in one direction in response to pressure in said cylinder, a second adjustable means associated with said spring means on the opposite side of said leaf-spirng means from said tirst adjustable means and on the opposite side of said fulcrum means from said rst adjustable means for adjusting the force exerted by said spring means on said piston, and a iiexible coupling element connected to said spring means and said throttle for operatively transmitting the movements of the piston to the throttle of the engine to open the throttle upon movement of said piston in response to an increase in uid pressure in said cylinder, and to permit the throttle to close upon movement of said piston in the opposite direction under the inuence of said spring when the fluid pressure in the cylinder is reduced.

3. An automatic control device for controlling the throttle of an engine operating a pump, said automatic control device comprising a housing having an elongated slot therein, a pressure responsive means in said housing, a conduit connecting said pressure responsive means with the outlet side of said pump whereby fluid under pressure from said pump produces a response in one direction, leafspring means in said elongated slot associated with and external to said pressure responsive means for opposing said response, adjustable stop means associated with said spring means for limiting the extent of said response, adjustable tension means associated with said spring means for varying the oposing force of said spring means, pivot pin means including a pin and means for positioning said pin in one of a plurality of positions between said adjustable stop means and said adjustable tension means for selecting ranges of pressures in said pressure responsive means for controlling said throttle, a flexible tension element extending between said leaf-spring means and the throttle of the engine for operatively transmitting said response of said pressure responsive means to the throttle of the engine to open the throttle of the increase in uid pressure in said pressure responsive means, and to permit the throttle to close upon a reduction of uid pressure in and under the inuence of said spring on said pressure responsive means, and means for changing the point of connection of said tension element relative to said spring means.

4. A method for adjusting a control device to control the throttle of an engine operating a pump in accordance with the difference in pump delivering pressures for idling and operating speeds as produced on a pressure responsive means which acts upon a leaf spring comprising positioning a fulcrum intermediate the ends of said spring and connecting a mechanical linkage between the throttle and a predetermined point on said leaf spring on one side of said fulcrum to select the pressure range for which said throttle is to -be moved from idle to operating positions, positioning one end of an adjustable screw against the other side of said leaf spring and adjusting said screw for idling throttle'speed and positioning a second adjustable screw on said one side of said fulcrum in the path of said leaf spring and adjusting said second screw to limit the operating speed of said engine by limiting thev leaf spring movement produced by said pressure responsive means in response to the pressure atV the upper end of said range. a

5. The method according to claim 4 comprising the step of moving said fulcrum to changelthe pressure range to which said control device responds. Y v 6. The method according to claim 4 including the step of changing the predetermined point of connection between said leaf spring and said linkage to change the pressure range for which said throttle is moved from idle Ato operating positions.

References v Cited UNITED STATES PATENTS 609,950 8/ 1898 Scott 103-35 2,373,143 4/ 1945 Samiran 103-16 X 2,634,681 4/1953 Rowell 103-16 2,690,712 10/ 1954 Foote 103-35 X 2,691,941 10/ 1954 Barklow 103-16 2,931,305 4/ 1960 Stratton 103-16 i DONLEY I. s'rooKlNG, Primary Examiner. 

1. AN AUTOMATIC CONTROL DRVIE FOR CONTROLLING THE THROTTLE OF AN ENGINE DRIVING A HYDRAULIC PUMP, SAID AUTOMATIC CONTROL DEVICE COMPRISING A HOUSING, A CYLINDER IN SAID HOUSING, A PISTON IN SAID CYLINDER, A CONDUIT CONNECTED TO ONE END OF SAID CYLINDER ND COMMUNICATING WITH THE OUTLET SIDE OF SAID PUMP, WHEREBY PRESSURE ON THE OUTLET OF SAID PUMP TENDS TO MOVE SAID PISTON AWAY FROM SAID ONE END OF SAID CYLINDER TOWARD THE OTHER END OF SAID CYLINDER, LEAF-SPRING MEANS IN SAID HOUSING AND HAVING A FIRST END ENGAGING SAID PISTON FOR MOVING SAID PISTON TOWARD SAID ONE END OF SAID CYLINDER AND A SECOND END, A PIVOT PIN ENGAGING SAID LEAF-SPRING MEANS INTERMEDIATE THE ENDS OF SAID LEAF-SPRING MEANS, A FIRST ADJUSTABLE SCREW MEANS POSITIONED TO ENGAGE SAID SPRING MEANS ON ONE SIDE THEREOF FOR LIMITING TRAVEL OF SAID SPRING MEANS IN RESPONSE TO PRESSURE IN SAID CYLINDER, A SECOND ADJUSTABLE SCREW MEANS ENGAGING THE OPPOSITE SIDE OF SAID SPRING MEANS FROM SAID FIRST SCREW MEANS AND AT A POINT ON THE OPPOSITE SIDE OF SAID PIVOT PIN FROM SAID FIRST SCREW MEANS FOR ADJUSTING THE FORCE EXERTED BY SAID SPRING MEANS ON SAID PISTON, AND COUPLING MEANS OPERATIVELY COUPLING SAID LEAF-SPRING MEANS TO THE THROTTLE TO OPEN THE THROTTLE IN RESPONSE TO AN INCREASE IN FLUID PRESSURE IN SAID CYLINDER AND TO PERMIT THE THROTTLE TO CLOSE WHEN THE FLUID PRESSURE IN SAID CYLINDER IS REDUCED. 